1. Field of the Invention
The invention is directed towards multi-dentate late transition metal polymerization catalyst complexes and their use in forming polymers from olefins or polar monomers and copolymers from olefins and polar monomers.
2. Description of the Related Art
Polymers and copolymers may be formed from olefinic monomers by using transition metal catalyst technology. Ziegler-Natta catalysts have been used for many years, while, in more recent years, metallocene catalysts have been preferred in certain applications, since the polyolefins produced via metallocene catalysis often possess superior properties. The most well known metallocene technology employs catalysts containing early transition metal atoms, such as Ti and Zr.
Even though polyolefins formed by such metallocene catalysts possess certain enhanced properties over polyolefins produced by conventional Ziegler-Natta catalysts, further improvements in properties such as wettability and adhesiveness may be possible. It is believed that including polar monomers in an olefinic polymer or copolymer would improve these, and possibly other, properties. Unfortunately, polar monomers tend to poison early transition metal catalysts.
Certain late transition metal complexes, such as those containing palladium and nickel, are more successful in incorporating certain polar monomers into polyolefins. However, most of these catalyst compositions are costly and produce highly branched polymers (e.g., 85-150 branches/1000 carbon atoms). Also, the functionalities are not in the chain, but at the ends of branches. Consequently, they are limited to polar monomer contents of about 15 mol % or less. Another disadvantage of these compositions is that they incorporate only a limited number of polar monomers, such as alkyl acrylates and vinyl ketones.
Recently, novel late transition organometallic catalysts have been made to address the aforementioned problems. More specifically, U.S. Pat. No. 6,037,297 to Stibrany et al., incorporated by reference herein, details group 11 (Cu, Ag and Au; new IUPAC notation) metal-containing catalyst compositions having a pseudotetrahedral geometry that are useful in forming polymers and copolymers having hydrocarbyl polar functionality. Other examples of group 11 metal-containing catalyst compositions are known. See, e.g., WO 98/35996 and JPA 11-171915, both to Shibayama, et al. and both incorporated by reference herein.
However, there is still a need to explore other group 11 metal complexes for use in polymerization processes. Ideally, these late transition metal complexes should be capable of forming olefinic polymers and copolymers containing polar monomers which are not highly branched, have polymer chain functionality and are capable of incorporating a wider variety of polar monomers.
The instant invention provides a late transition metal complex which can be used with an activating cocatalyst to produce polymers and copolymers. Further, the instant invention can be used to produce polymers and copolymers containing polar monomers. More specifically, the metal complex may be activated by a cocatalyst which is then used to polymerize olefins and copolymerize olefins with polar monomers. Hence, the invention also provides methods for polymerizing olefins, as well as copolymers having polar monomers incorporated therein.
In one embodiment, the invention provides a composition having the formula LMXZn, wherein M is selected from the group consisting of Cu, Ag and Au; X is selected from the group consisting of halide, hydride, triflate, acetate, borates, C1 through C12 alkyl, C1 through C12 alkoxy, C3 through C12 cycloalkyl, C3 through C12 cycloalkoxy, aryl, thiolate, nitrate, sulfate, nitrile, hydroxide and any other moiety into which a monomer can insert; Z is selected from the group consisting of halide, hydride, triflate, acetate, borate, C1 through C12 alkyl, C1 through C12 alkoxy, C3 through C12 cycloalkyl, C3 through C12 cycloalkoxy, aryl, thiolate, carbon monoxide, nitrate, nitrile, hydroxide, sulfate, olefins, water, any other neutral coordinating ligand and any other moiety into which a monomer can insert; n equals 0, 1 or 2; and L is a multi-dentate nitrogen-containing ligand.
In another embodiment, the invention is a catalyst composition comprising the reaction product of a metal complex having the formula LMXZn, as defined above, and an activating cocatalyst. This embodiment of the invention is particularly useful in polymerization chemistry.
In yet another embodiment, the invention provides a method for using the composition to produce polymers and copolymers which contain polar monomer units. The method includes contacting the monomers under polymerization conditions with a catalyst composition comprising a composition having the formula LMXZn, as defined above, and an activating cocatalyst. Optionally, an oxidizing agent may also be employed during this process.
In a further embodiment, the instant invention provides a novel olefin polymerization process based on the use of a group 11 transition metal complex having the formula MXZn, as defined above; a multi-dentate nitrogen-containing ligand L; and an activating cocatalyst, which are all contacted with monomers in situ. Unlike Atom Transfer Radical Polymerization (ATRP), the instant invention does not use an alkyl halide initiator, but instead uses a cocatalyst, and can be used to prepare homo- and co-polymers of aliphatic olefins. Further, unlike U.S. Pat. No. 6,037,297, this embodiment of the invention teaches that the use of a preformed metal complex is not a prerequisite. More specifically, it is theorized that the metal complex may be formed in situ by adding the metal compound with a ligand at the same time cocatalyst is added. Hence, the advantages of the instant invention include an in situ method for forming an active catalyst composition which is a step-saving, cost-saving process.
These and other features, aspects and advantages of the present invention will become better understood with regard to the following description and appended claims.